Most vehicle fuel tanks include a fuel level sensor for outputting a signal representative of the level of fuel in the tank. The signal can be used to drive a fuel gage, illuminate a warning light, etc.
One common fuel level mechanism is composed of a float on a wire arm that is supported in a wiper and bushing on a frame. The frame holds a ceramic card that includes a resistive strip for creating an electrical resistance when the strip touches a contact installed in the wiper. As critically recognized herein, while effective, the arrangement summarized above requires a considerably large space to accommodate a relatively large range of motion of the wire arm with float. One reason the large range of motion is required is to overcome the frictional force between the contact and the resistive strip by creating a relatively long moment arm on the end of which is the float, which long moment arm is sufficient to overcome the frictional force.
Another type of fuel level sensor uses the same basic concepts as the arrangement discussed above, with the difference being that a float is constrained to vertical movement against a vertically oriented conductive strip and resistor element. Although this configuration needs relatively less space than a float with wiper arm assembly, it uses a bigger float, again to overcome the frictional force between the contact assembly and the resistive strip.
Accordingly, as critically recognized herein, because of the size and complexity of these designs, they are used only in fuel tanks of cars and those few motorcycles that are equipped with relatively large fuel tanks. Vehicles such as smaller motorcycles or other vehicles with small fuel tanks cannot easily be equipped with the above-discussed fuel level sensors.